Interface MidiDevice

MidiDevice is the base interface for all MIDI devices.
Common devices include synthesizers, sequencers, MIDI input ports, and MIDI
output ports.

A MidiDevice can be a transmitter or a receiver of
MIDI events, or both. Therefore, it can provide Transmitter
or Receiver instances (or both). Typically, MIDI IN ports
provide transmitters, MIDI OUT ports and synthesizers provide
receivers. A Sequencer typically provides transmitters for playback
and receivers for recording.

A MidiDevice can be opened and closed explicitly as
well as implicitly. Explicit opening is accomplished by calling
open(), explicit closing is done by calling close() on the MidiDevice instance.
If an application opens a MidiDevice
explicitly, it has to close it explicitly to free system resources
and enable the application to exit cleanly. Implicit opening is
done by calling MidiSystem.getReceiver and MidiSystem.getTransmitter. The MidiDevice used by
MidiSystem.getReceiver and
MidiSystem.getTransmitter is implementation-dependant
unless the properties javax.sound.midi.Receiver
and javax.sound.midi.Transmitter are used (see the
description of properties to select default providers in
MidiSystem). A MidiDevice
that was opened implicitly, is closed implicitly by closing the
Receiver or Transmitter that resulted in
opening it. If more than one implicitly opening
Receiver or Transmitter were obtained by
the application, the decive is closed after the last
Receiver or Transmitter has been
closed. On the other hand, calling getReceiver or
getTransmitter on the device instance directly does
not open the device implicitly. Closing these
Transmitters and Receivers does not close
the device implicitly. To use a device with Receivers
or Transmitters obtained this way, the device has to
be opened and closed explicitly.

If implicit and explicit opening and closing are mixed on the
same MidiDevice instance, the following rules apply:

After an explicit open (either before or after implicit
opens), the device will not be closed by implicit closing. The only
way to close an explicitly opened device is an explicit close.

An explicit close always closes the device, even if it also has
been opened implicitly. A subsequent implicit close has no further
effect.

To detect if a MidiDevice represents a hardware MIDI port, the
following programming technique can be used:

isOpen

getMicrosecondPosition

long getMicrosecondPosition()

Obtains the current time-stamp of the device, in microseconds.
If a device supports time-stamps, it should start counting at
0 when the device is opened and continue incrementing its
time-stamp in microseconds until the device is closed.
If it does not support time-stamps, it should always return
-1.

Returns:

the current time-stamp of the device in microseconds,
or -1 if time-stamping is not supported by the device.

getMaxReceivers

int getMaxReceivers()

Obtains the maximum number of MIDI IN connections available on this
MIDI device for receiving MIDI data.

Returns:

maximum number of MIDI IN connections,
or -1 if an unlimited number of connections is available.

getMaxTransmitters

int getMaxTransmitters()

Obtains the maximum number of MIDI OUT connections available on this
MIDI device for transmitting MIDI data.

Returns:

maximum number of MIDI OUT connections,
or -1 if an unlimited number of connections is available.

getReceiver

Obtains a MIDI IN receiver through which the MIDI device may receive
MIDI data. The returned receiver must be closed when the application
has finished using it.

Usually the returned receiver implements
the MidiDeviceReceiver interface.

Obtaining a Receiver with this method does not
open the device. To be able to use the device, it has to be
opened explicitly by calling open(). Also, closing the
Receiver does not close the device. It has to be
closed explicitly by calling close().

getTransmitter

Obtains a MIDI OUT connection from which the MIDI device will transmit
MIDI data The returned transmitter must be closed when the application
has finished using it.

Usually the returned transmitter implements
the MidiDeviceTransmitter interface.

Obtaining a Transmitter with this method does not
open the device. To be able to use the device, it has to be
opened explicitly by calling open(). Also, closing the
Transmitter does not close the device. It has to be
closed explicitly by calling close().